1. Field of the Invention
This invention relates to a polymeric composition. More particularly, this invention relates to a polymeric composition comprising an olefin polymer.
2. Prior Art
Olefin polymers and compositions comprising such polymers are, of course, well known in the prior art. Both the polymers and various compositions comprising such polymers are frequently used in molding applications to prepare molded articles as well as in the preparation of films, sheets, textile coatings and the like. Use of the various olefin polymers in many of these applications is, however, frequently restricted due to the poor impact resistance of the products thus produced. Use of the olefin polymers in many of these applications is also limited due to poor tensile strength, poor clarity in the various products produced and whitening or "blushing" of certain such products when subjected to stress or impact.
Heretofore, several methods have been proposed for use in an effort to avoid one or more of these problems. For example, it has heretofore been proposed to incorporate a selectively hydrogenated triblock copolymer, having terminal polymeric blocks of a vinyl aromatic monomer and a central polymeric block prepared originally with a conjugated diolefin and subsequently hydrogenated, into a polymeric composition comprising one or more olefin polymers primarily for the purpose of improving impact resistance and to reduce whitening or "blushing" such as taught in U.S. Pat. No. 3,299,174. The improved impact resistance is, however, apparently, achieved at the expense of losing other properties such as stiffness, particularly when polypropylene is the olefin polymer used. It has, therefore, been proposed to incorporate crystalline polyethylene into a polymeric composition comprising propylene and a hydrogenated block copolymer so as to achieve a better balance between stiffness and impact resistance as is taught in U.S. Pat. No. 4,178,328. It is also known in the prior art to incorporate a relatively high polymerized styrene content linear or radial block copolymer comprising styrene polymeric blocks and butadiene polymeric blocks into a composition comprising crystalline polypropylene to produce resin products having a pearl-like pattern or luster and excellent impact strength and hinging properties as taught in U.S. Pat. No. 4,499,238. It is further known in the prior art to add a copolymer of ethylene and vinyl acetate to a polymeric composition comprising a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene and polypropylene to produce products having improved softness, transparency, high temperature strength and molding characteristics as taught in U.S. Pat. No.4,588,777.
As is well known in the prior art, incorporation of a hydrogenated linear or radial block copolymer comprising two or more blocks containing predominantly aromatic hydrocarbon monomers and at least one polymeric block containing predominantly conjugated diolefin monomers into a polymeric composition comprising one or more olefin polymers will, indeed, solve several of the problems which have hampered the various products produced from olefin polymers. Polymeric compositions comprising an olefin polymer and a linear or radial block copolymer comprising at least two polymeric blocks containing predominantly monoalkenyl aromatic hydrocarbon monomer units and at least one polymeric block containing predominantly conjugated diolefin monomer units have not, however, been widely accepted commercially, apparently due to the relatively high cost of the block copolymer component. The need, then, for a polymeric composition comprising one or more olefin polymers, the products from which will be free from one or more of the aforementioned deficiencies, which polymeric composition can be produced at a lower cost is believed to be readily apparent.